Citing recent heavy thunderstorms, city officials issued a recommendation to boil water Thursday after higher than normal levels of particles were detected in the city?s drinking water supply.
Officials say the particles can interfere with the water chlorination process, potentially causing problems for people with compromised immune systems.

The discovery was made at about 2 a.m. Thursday at the Hillview reservoir, on the Bronx-Yonkers border, one of three reservoirs that supply drinking water to New York City, said Sandra Mullin, a spokeswoman for the Department of Health and Mental Hygiene.

While the affected water was diverted, health officials, citing ?an abundance of caution,? suggested that infants, the elderly, pregnant women and New Yorkers with conditions that compromise their immune systems use either boiled or bottled water as a precaution until noon Friday.

The recommendation applies to those with HIV/AIDS, especially those with CD4 counts less than 200; those with leukemia; and those who have received bone marrow transplants, officials said.

The Health Department also asked doctors to increase testing for parasitic illnesses and immediately report any diseases, as well as any increase in gastrointestinal symptoms.